The present invention relates to a fuel cell system capable of performing intermittent operation, an operation method thereof, and a fuel cell vehicle, particularly to a technology which is effective in preventing the fuel economy from being lowered by a wasteful discharge of fuel gas.
For example, as a power generating system for a fuel cell vehicle, there is known a fuel cell system which can directly extract, as electrical energy, chemical energy obtained from an oxidation-reduction reaction between fuel gas and oxidation gas. In this type of fuel cell system, various valves (pressure regulating valve, cutoff valve, and the like, for example) are disposed in a hydrogen supply passage for supplying hydrogen from a hydrogen supply source to a fuel cell, and the hydrogen from the hydrogen supply source is regulated (pressure reduction) to predetermined pressure and then supplied to the fuel cell.
When any abnormality occurs in these valves or a control device, the pressure inside the hydrogen supply passage abnormally increases. Therefore, Japanese Patent Application Laid-Open No. 2002-134139, for example, discloses a technology in which a relief valve is provided in a hydrogen supply passage so that the hydrogen can be discharged to the outside by opening the relief valve when the pressure inside the hydrogen supply passage is pressurized to predetermined pressure or higher.
In the technology proposed in Japanese Patent Application Laid-Open No. 2002-134139, the hydrogen is discharged to the outside when the pressure inside the hydrogen supply passage is pressurized to predetermined pressure or higher, thus this technology is effective in preventing damage to the fuel cell, gas supply passage, and valves, but there is a concern that the fuel economy is lowered due to the discharged hydrogen.